The Filtrex FX10-CL2 10 micron carbon filter fits other filter housings that take a standard size 10"x2.5" cartridge. It will replace OMNI CB3 filter. Other systems that can use FX10-CL2 are Culligan, American Plumber, Aqua Pure, Pentek, Ametek, US Filter, Hydrologic Small Boy Carbon filter, and other brands of housings that require a standard 10" Filter Cartridge. Filter should be changed every 3 to 6 months.